The subject matter disclosed herein relates to seal assemblies and, more particularly, to devices for sealing butt gaps between segments of a seal assembly in a rotary machine.
The design and operation of some rotary machines (e.g. steam turbines, gas turbines, etc.) include the use of segmented seal assemblies. These seal assemblies may include a number of segments which are assembled together to form a substantially continuous body (e.g., a body which is largely but not wholly uniform in a surface and/or shape), the segments forming a circle with small gaps between a distal end of each segment. The segments are disposed against one another so as to form a seal or barrier. During operation, these segmented seal assemblies substantially fluidly isolate/separate portions of the turbine. However, some spacing/clearances may be required between the segments of these segmented seal assemblies to allow for variances in thermal expansion rates and steam turbine operating temperatures. This limitation on clearance tightness may require spaces/breaks (e.g. butt gaps) between the circumferential ends of adjacent segments of the seal assembly, and thereby enable fluid leakage through the seal assembly. Fluid leakage through the seal assembly may damage turbine components and/or decrease the efficiency of the steam turbine. Some steam turbines may limit leakage through these thermal spaces by placing a sealing strip in contact with an outside diameter surface of the segment head flange. However, this strip may fail to prevent radial leakage through the axial gaps between the side of the head flange and the side surface of the housing. Further, leakage may pass around the distal ends of the strip and through the butt gap perpendicular to the axial mating surface between the seal assembly and the housing.